Fluorescent lights, among the more cost-effective lighting options, sometimes require a ballast repair when the light fails to illuminate or begins flickering. Troubleshooting one of these ballasts is usually simple, takes little time, and is something even the least experienced homeowner can do. Use the information below to troubleshoot a ballast that may be failing in one of your fluorescent lights.
Never work on an electrical device without first shutting off power to it. This includes light fixtures. But, in disconnecting power from a ballast, there is more involved than simply flipping a switch. Even when the power is cut off to a ballast, the ballast momentarily retains some power until all power from the electrical circuit dissipates. This dissipation will usually take no more than 10 to 15 seconds. Still, you will need to shut off power at your circuit breaker box and check the light fixture with a multi-meter to be sure there is no current present in the ballast.
Removing Fluorescent Bulbs
Fluorescent bulbs (tombstones) are quite fragile, and handling them is important to keep from breaking them. When removing them, you will save time and frustration if you place them where they are less likely to become broken and where you'll find them more easily when it's time to return them to the fixture.
When the covering is removed from the fixture you may notice oil that has leaked from the ballast. This will be an indication that you will need to replace your ballast because the heat has caused the internal seal to rupture.
Testing for Continuity
In testing a ballast that has stopped working, you'll need to check its wiring for breaks or interruptions in its wiring. To do this checking, you'll need to know something about the wiring. Usually, each fixture will have one or two wires connected to it, one (usually blue or yellow) is the power line. The other wire, which is usually white, is neutral. If you test the wires for continuity between the power line and neutral line, and if there is continuity, this will tell you there is no disruption or break in this circuit.
Testing for Resistance
In testing for resistance in the circuitry when your multimeter is in the "ohms" setting and each of its probes is touching either the neutral (white) wire or the power (colored) wire, check your meter for any shorts in these wires. This check should be made on each pair of wires.
Testing the Transformer
Transformer wires from the ballast's power lines, when touching the black and white wires with separate probes on your meter and observing the meter's reading, should tell you whether these circuits are good or whether the ballast should be replaced.
Possible Loose or Disconnected Wiring
If in making the checks described above, you find that all circuits are good, the last check you'll need to make will be of the tombstones and their wiring. Sometimes wires to them can become loose and can lose connectivity. A quick check of these connections will reveal any problems with these connections.